Topographic Influence on the Motion of Tropical Cyclones Landfalling on the Coast of China

Abstract

Abstract A few recent numerical studies investigated the influence of a continent, which is much larger in size than islands, on the track of a landfalling tropical cyclone. It has been found that land surface roughness and temperature tend to make a tropical cyclone move toward the continent. In this study, the effect of the elevated terrain on the western part of mainland China on landfall tracks is examined through idealized numerical experiments, in which an initially axisymmetric vortex is embedded into a monsoon trough and takes a landfall track across China’s mainland. It is found that the effect of the elevated terrain on the western part of mainland China can enhance the southerly environmental flows in the low and midtroposphere, leading to an additional landward component of tropical cyclone motion, suggesting that forecasts for tropical cyclone tracks over land should take into consideration the change in thermal condition over the continent. The study suggests that the increased duration of tropical cyclone overland tracks observed in China may be associated with the reduction of the thermal forcing over the Tibetan Plateau.